Mark 9:16-18

16“What are you arguing with them about?” he asked. 17A man in the crowd answered, “Teacher, I brought you my son, who is possessed by a spirit that has robbed him of speech.

18Whenever it seizes him, it throws him to the ground. He foams at the mouth, gnashes his teeth and becomes rigid. I asked your disciples to drive out the spirit, but they could not.”